Gasification of biomass by thermal methods involving pyrolysis and/or partial oxidation is known as a method to produce a synthesis gas, composed of carbon oxides and hydrogen, or a fuel gas. Many of the known methods use a dry biomass feedstock with less than 10 wt % moisture. However, much of the biomass resource contains higher levels of moisture, more typically 50 wt % and some even consist of wet biomass, or biomass in water slurries at 85 wt % moisture or higher. One approach to efficiently process such wet biomass is gasification employing an active catalyst in a pressurized water environment (e.g., hydrothermal gasification).
However, when treating wet biomass by hydrothermal gasification, constituents that are commonly inherent in the feedstock can poison and/or foul the catalyst making long-term and/or continuous operation difficult to achieve. Accordingly, a need for apparatuses and methods for hydrothermal gasification of wet biomass exist.